Planetary Roller Screw Taper Grinding for Uniform Load Distribution
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Solution Overview
Problem
Existing machining methods for planetary roller screw mechanisms face challenges in achieving uniform load distribution, leading to high machining costs and technical difficulties, making them unsuitable for batch production and popularization.
Innovation Solution
A roller taper grinding method that involves determining basic parameters, establishing deformation and force balance equations, iteratively computing an optimal grinding taper angle, and setting process parameters for efficient machining using a machine tool to improve load distribution uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thread-pitch-varying machining is used to achieve uniform load distribution, then load distribution uniformity is improved, but machining precision requirements become extremely high and machining cost increases
Solution Approach 1:
The patent changes the geometric parameter of the roller by introducing a taper angle (α = 0.5°-2.0°) on the roller surface. This parameter change modifies the contact geometry between the roller and screw thread, enabling uniform load distribution across multiple threads without requiring extremely precise control of thread pitch variations. The taper angle serves as a controllable parameter that compensates for load concentration issues.
Solution Approach 2:
The patent applies local quality by creating a non-uniform surface on the roller through taper grinding. The roller surface has different angles at different locations (tapered from one end to the other), which creates varying contact conditions along the roller length. This local variation in surface geometry ensures that load is distributed uniformly across multiple threads of the screw, rather than concentrating on a single thread.
2Manufacturing precision
If axial-speed-varying machining is used to achieve uniform load distribution, then load distribution uniformity is improved, but machining implementability deteriorates due to transmission chain limitations
Solution Approach 1:
Instead of varying the axial speed during machining (which requires complex transmission control), the patent changes the geometric parameter of the workpiece itself by applying a taper angle to the roller surface. This parameter change achieves the same load distribution effect through a simpler, more implementable machining process that does not require time-varying speed control.
3Manufacturing precision
If roller-segmenting machining is used to achieve uniform load distribution, then load distribution uniformity is improved, but productivity decreases due to reduced grinding efficiency
Solution Approach 1:
The patent applies segmentation by dividing the roller surface into different angular zones through taper grinding. The roller surface is segmented such that different portions contact different threads of the screw at different times during rotation. This segmentation of the contact zone achieves uniform load distribution across multiple threads while maintaining continuous grinding of the entire roller surface, thus preserving productivity.
4Manufacturing precision
If a special-purpose uniform load distribution machining method is developed for planetary roller screw mechanism, then load distribution uniformity is improved, but device complexity increases
Solution Approach 1:
The patent uses parameter changes (taper angle) as a simple and effective means to achieve uniform load distribution. By controlling just one geometric parameter (the taper angle α) during roller grinding, the method achieves load uniformity without requiring complex multi-parameter control systems or sophisticated machining procedures.
Solution Approach 2:
The patent applies preliminary action by pre-grinding the roller surface with a specific taper angle before assembly. This preliminary geometric modification ensures that when the planetary roller screw mechanism is assembled and operated, the load will be uniformly distributed across threads without requiring any additional complex control mechanisms during operation.
Data Source
AI summary
Disclosed is a roller taper grinding method for a planetary roller screw mechanism. The method includes steps as follows: step 1: determining basic parameters and a bearing capacity of a planetary roller screw mechanism to be machined; step 2: establishing deformation and force balance equations of the planetary roller screw mechanism according to the basic parameters and the bearing capacity of the planetary roller screw mechanism determined in step 1; step 3: iteratively computing an optimal grinding taper angle of roller grinding according to the deformation and force balance equations established in step 2; step 4: determining process parameters of roller grinding; and step 5: grinding a roller taper of the planetary roller screw mechanism by a machine tool according to the process parameters determined in step 4.